<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
*{margin:0;padding:0;}
button{width:20px;height:20px;}
</style>
</head>

<body>
	<button id="myButton"></button>
    <script>
    	var button=document.getElementById('myButton');
		button.focus();
		console.log(document.activeElement === button);//true;
		console.log(document.hasFocus());//true;
		
		
    </script>
    
</body>
</html>
